The invention relates to a semiconductor array having a plastic casing and a cooling portion which is at least partly not embedded in the plastic.
Electrical equipment is today preferably fitted with semiconductor components such as transistors or integrated circuits with the aid of automatic machinery. Semiconductor components with platic casings and suitable for clip assembly are particularly well suited for automatic fitting.
Power components such as power transistors which are embedded in plastic casings have, as is known, cooling plates on their undersides to cool the semiconductor component. When installing a power transistor with plastic casing and cooling plate, two cases must be distinguished: in one case the cooling plate is mounted insulated on a base, for example a chassis or cooling sheet, while in the other case the cooling plate is mounted uninsulated on a base. In the second case, the cooling plate has the same potential as the base. If a semiconductor component has to be mounted insulated on a base so that it does not assume the potential of the base, materials with good thermal conductivity and electrical insulation properties are required, and must be mounted in strips between the cooling plate and the base (cooling sheet). It is obvious that this type of mounting is not conductive to easy fitting.
For that reason, the method was introduced of using, in the case where a power transistor has to be mounted insulated on the base, power transistors completely embedded in plastic casings together with their cooling plates, and, in the other case where no insulation is necessary between cooling plate and cooling sheet or base on which the transistor is mounted, transistors in which the cooling plates are not surrounded by plastic at least on their undersides.
According to the prior art, therefore, two different plastic casings and so two different production lines are necessary, depending on the application, requiring high investment costs.